Over a hundred years ago, wireless electric energy transmission or wireless power transmission technology was already tested by American inventor Nicola Tesla via experiments. In year 2006, researchers in Massachusetts Institute of Technology (MIT) successfully lit a 60 W bulb at a distance of about 2 cm with a efficiency of 40% using the physical resonance technologies, and this experiment was not only a reproduction of the Tesla experiments, but also another new breakthrough in the wireless electric energy transmission technologies and it has led a wave for researches about wireless electric energy transmission.
Wireless electric energy transmission technology is an approach for transmitting electric energy that has a prosperity of wide utilization and that has advantages such as it is safe, reliable, flexible and convenient etc.; and this technology has been valued around the world and is more and more widely used in the location where it is unsuitable or inconvenient to use wire-contacted power transmission, such as in the case of power supply for implanted medical devices, mobile electronics, robots, railway vehicle etc., and is expected to replace traditional plugged charging in terms of wireless charging of low power electronics in the near future.
The wireless electric energy transmission systems at present are all implemented based on inductance and capacitance of integer order, and its resonant frequency merely depend on the values of inductance and capacitance without the need to consider the order number of the elements, and thus the degree of design freedom is low. Meanwhile, the actual systems are fractionally ordered in nature, however, in view of most order numbers used in the practice are approximately 1, the cases of fractional order are completely neglected. In traditional electric power transmission systems that are designed via integer order modeling, the errors between theory and practice may be very large under certain conditions.
The concept of fractional order devices (such as fractional order capacitance and fractional order inductance) originates from the occurrence of fractional order calculus, whereas the concept of fractional order calculus has a history of over 300 years and arose nearly at the same time as the integer order calculus. However, since the fractional order calculus is relatively complex and there is always no very good numerical analysis tools, it stays always in the phase of theoretical analysis. In the last few decades, due to the development of biotechnologies and polymer materials, people discovered that the integer order calculus cannot quite well explain the phenomena occurring in the nature, and thus the fractional order calculus began to be valued and to be used in engineering, and its researches and utilization in the automation field was increasingly becoming perfect. Meanwhile, fractional order devices for both ends have been manufactured in laboratories. However, some special characteristics of fractional order circuits and system have not yet been studied, and its utilization in the field of wireless power transmission is even not mentioned.
In view of the current fractional order elements have not yet been utilized in the field of wireless power transmission and there is no related report about the utilization and its performance after the utilization cannot be anticipated, thus a further study is necessary.